Vitriolic barnacles are a creature fabricated by Dr. Barlow. They can be used to melt metal, and are used to melt kraken nets by Deryn in the Ottoman Empire. Because of their effect on metal, they are stored in glass jars.
In the seriesEdit
Dr. Barlow show the barnacles to Deryn when she is given her secret misson to destroy Ottoman kraken nets in the straits of Gallipoli on the Leviathan's bridge. Deryn wonders how she and her men would be able to destroy strong metal kraken nets. The metal tongs that Dr. Barlow places in the jars filled with the vitriolic barnacles melt, showing that the barnacles could also melt kraken nets. The kraken nets need to be melted to allow a behemoth to pass through the strait.
During her mission, only Deryn can know about the barnacles, in case any of her men are captured by the Ottomans. Deryn places the barnacles on the kraken nets during her mission, and must be careful to place them with enough distance apart that they will not become territorial, but will still be able to breed.